main() {
  var a = 'hello';
  print(a);
  final num b = 34;
  print(b);

  const double d = 3.23;
  print(d);
  var cc = [1, 2, 3, 4];
  for (var x in cc) {
    print(x);
  }
  for (var i = 0; i < 9; i++) {
    print(i);
  }

  var we=23;
  int wer=45;
  String name='rtt';
  const id =45;
  dynamic po='Didot';
  final int pr =45;
  Object mk ='op';
  print('this is $id');
  print('this name $name');

 bool uo=3>4;
 if (uo){
   print('object');
 }else if(!uo){
   print('www');
 }else{
   print('object');
 }


 var  rr=0;
 dynamic opp=0;
 //以上二种都可以推到类型
  int awee=45;
  int oppp=45;
  const int iu=45;
  final int mm=0;





}


class  User{

}

class Info<T extends User>{
 void  inf(){
   try{
     int age =(23/0) as int;
     throw "异常";
   }
   on Exception{
     print('thisi is app');
   }catch (e){
     print('thisi is web');
   }finally{
     print('this is web');
   }



 }
}

